Method for monitoring a communication system

ABSTRACT

A method is provided for monitoring operational performance of a communication system including a mobile telephone unit and a plurality of control stations, while the mobile telephone unit is in operation within the communication system. The method makes use of signals passing between the mobile telephone unit and one of the plurality of control stations during such operation. The method including the steps of establishing an identity of the mobile telephone unit from said signals and utilizing predetermined operational characteristics of the signals as a source of information for monitoring operation of the mobile telephone unit. Therefore, the method can detect automatically a faulty mobile telephone unit or control station during operation of the mobile telephone unit.

BACKGROUND OF THE INVENTION

This invention is concerned with monitoring electronic systems.

In particular, but not exclusively, the present invention is concernedwith equipment for facilitating the diagnostic testing/monitoring ofmobile telephone units or more generally mobile transmitter/receiverunits.

A particular form of such mobile communication system is known as acellular mobile communications system.

For convenience and without limitation of the scope of the practicalapplication of the methods and apparatus of the invention, for thepurposes of facilitating discussion of such methods and apparatus of theinvention, the use thereof in relation to a cellular mobilecommunication system will be considered in detail.

In brief, a cellular mobile communication system is a communicationnetwork involving a number of so-called cells which makes it possiblefor a transmitter/receiver unit installed in a motor or other vehicle,to communicate with conventionally provided telecommunications systemsby way of a network of transmitter/receiver aerials or beacons eachdefining the `focal point` or node of a cell and each of which are sopositioned in predetermined locations relative to each other across thezone or region within which the network is designed to be operative, aseffectively to form inter-related groups of cells.

In a known system, each cell group includes seven individual cells whosearrangement within a group can be likened to a honeycomb. In this systemthe groups themselves are mutually arranged within the system so as toexpand the extent of operation of the group honeycomb.

Each cell includes a beacon which is responsive to a predeterminednumber of channels selected from the total number of channels (amountingto several hundred) involved in the overall system. In addition, eachsuch cell of a group has uniquely ascribed thereto a particular group ofthe channels whereby no two adjacent cells in the overall system haveprecisely the same channel grouping.

The underlying concept is that when a mobile transmitter/receiver unitis located within the effective area of any one beacon and the userthereof requires to communicate with a particular telephone number,national or otherwise, the mobile equipment enables him to dial, in amanner similar to the dialling of a conventional telephone the requirednumber. The mobile equipment is capable of opening a communicationchannel to the required telephone subscriber by way of the beacon in thecell within which the vehicle happens to be located at the time ofinitiating operation of the equipment.

As the vehicle with the mobile unit moves further away from any onebeacon and moves nearer to any other beacon in the system, the systemitself, where necessary, automatically transfers the communication pathfrom beacon to beacon.

Control arrangements provided within the beacon network of the system,and those involved in the mobile equipment ensures that anycommunication link that has been established is maintained as thevehicle moves from the ambit of one beacon to that of the next beaconalong the route of the vehicle. Thus the mobile unit is automaticallyeffectively transferred from one beacon to another without anyinterference with (i.e., breaking the communication connectionestablished) the communication path between the mobile unit and thecalled number. These operations are effected without any action by theuser.

From the forgoing it will be appreciated that the equipment involved ishighly complex, and that having regard to this complexity it has beenfound that it is essential that the actual mobile units involved shouldalways operate within their operational specifications to ensure theoptimum operational efficiency of the system overall.

It will also be appreciated that since the communication system involvesprovision of a very large number of relatively narrow (frequency-wise)communication channels between the mobile telephone units and thenetwork of so-called base channels it is important that any mobiletelephone unit should always operate within the frequency limits of anychannel to which it is allocated so as to avoid any operationalinterference between channels.

In practice, if the operational parameters of any mobile telephone unitshould drift in such manner that the operational bandwidth thereofoverlaps the frequency limits of adjacent channels any mobile telephoneunit allotted to these adjacent channels may well be prevented fromefficient operation.

A further problem arises in that the operation of a telephone unit whoseoperational frequency has spread i.e., whose frequency response hasdrifted, outside the allowed band width of a channel, can adverselyaffect the transfer of telephone communication paths from node to node.

With regard to this known equipment, experience has shown that it is notuntil the user of the telephone notices, normally during actual use ofthe equipment, that the performance of the mobile telephone is not asgood as expected or as previously experienced does the user considertaking corrective action to have the mobile telephone equipment involvedtested and, if necessary, repaired.

It will be apparent that by the time the actual user has realized thatthe equipment has become defective there is every possibility thatprogressive ongoing malfunctioning equipment could have reached thestage in which it is and may have been for a considerable period of timeseriously adversely interacting with the equipment of other users, andthereby reducing the efficiency of operation of such other user'sequipment and also the operation of the system overall.

OBJECTS OF THE INVENTION

It is an object of the present invention to provide methods and/orapparatus which facilitates the efficient effective operation of mobiletelephone systems.

STATEMENTS OF THE INVENTION

Broadly, according to the invention there is provided a method ofuniquely identifying any mobile telephone unit in operation within acommunications system involving a plurality of controllocations/nodes/beacons/base stations or the like, whilst the mobileunit is in operation within the communication system by making use ofsignals passing between a mobile telephone unit and any operationallyconvenient control location/node/beacon/base station or the like duringsuch operation.

Also according to the present invention there is provided a method ofmonitoring/measuring the operational performance of any mobile telephoneunit in operation within a communications system involving a pluralityof control locations/nodes/beacons/base stations, whilst the mobile unitis in operation within the communication system by making use of signalspassing between a mobile telephone unit and any controllocation/node/beacon/base station during such operation, characterizedby the steps of establishing the identity of the mobile station fromsaid signals and utilizing predetermined operational characteristics ofthe signals as a source of information for said monitoring/measuring.

Preferably, the signals utilized for such identification arepredetermined parameters of radio frequency signals involved in thecommunication system.

Conveniently, the unique identification of a mobile unit is establishedduring the initial stages of the establishment of a communication pathbetween the mobile unit and the remainder of the system.

Preferably, the unique identification of a mobile unit comprisesdetection of the mobile identity number of the mobile unit and thenumber of the channel within which it is operational at the time of theidentification.

Conveniently, following such identification predetermined operationcharacteristics/parameters of the mobile unit are monitored and theresults of such monitoring are utilized for presenting/recording thevalues of the characteristics/parameters monitored.

In accordance with a further aspect of the invention the operationalperformance of apparatus for establishing communication paths for amobile unit within a communication system involving a plurality ofcontrol locations/nodes/beacons/base stations or the like with which themobile units are arranged operationally to be able to communicate ismonitored whilst communication paths between mobile units and the systemare in operation.

Broadly, according to a still further aspect of the invention there isprovided apparatus for enabling any mobile telephone unit arranged foroperation with a communications system involving a plurality of controllocations/nodes/beacons /base stations or the like; to be uniquelyidentifiable from any such control location/node/beacon/base station orthe like whilst the mobile unit is in operation within the communicationsystem.

Conveniently, the control signals transmitted from the controllocation/node/beacon/base station or the like are utilized for affectingsaid unique identification.

Preferably, arrangements are provided for enabling at least onepredetermined operational characteristic/parameter of a mobile telephoneunit arranged for operation with the communications system, to beremotely monitored/checked whilst the mobile unit is operation withinthe communication system.

Broadly, according to another aspect of the invention there is providedapparatus for which can be configured for monitoring the performancecharacteristics of the signal transmitting/receiving equipment of a basestation of a cellular communications system and/or the performancecharacteristics of any mobile unit from time to time utilized the basestation in the establishment of a channel communication path, thearrangement being such as to enable, for the base station and/or for amobile unit, predetermined operational characteristics/parameters to bemonitored during the operation thereof within the communication system.

In accordance with a preferred aspect of the invention there is providedapparatus for decoding the control information transmitted between abase station and a mobile unit in such manner that whilst acommunication path is established between the control/base station and amobile unit predetermined ones of the operational parameters of themobile unit can be measured/monitored whilst the mobile unit is inoperation.

Preferably, the apparatus of the invention incorporates means fordecoding the channel selection control information transmitted, by acontrol/base station to a mobile unit requiring to establish a telephoneconnection with another number, to the calling mobile unit to specifythe channel to be used and means for automatically recording the mobileidentity number or the like of the calling mobile unit, for performing apredetermined sequence of measurements of the operational parameters ofthe mobile unit and for recording any measurements made.

In a further arrangement the signal emanating from the mobile unit isutilized for the purposes of the present invention.

In a particular embodiment the apparatus of the invention is arranged tomonitor/measure inter alia the following operational parameters:

carrier frequency error;

supervisory audio tone frequency;

Supervisory audio tone deviation;

signalling tone frequency;

signalling tone deviation;

peak voice deviation; and

input power received from the mobile unit.

It will be understood that the apparatus and methods of the inventionare not limited to the above specifically mentioned parameters.

The data derived from such measurement is conveniently stored bysuitable computer arrangements and is arranged to be presentable in theform of a composite computer `print-out`.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention and to show how to carry thesame into effect reference will now be made to the accompanying drawingsin which:

FIG. 1 very schematically represents a group of adjacent cells in acellular communication system illustrating the manner in which thecellular network is functionally arranged;

FIG. 2 very schematically illustrates the system of the presentinvention; and

FIG. 3 is a flow chart illustrating the monitoring steps performed bythe apparatus of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIG. 1 of the drawings this Figure illustrates inschematic outline the effective area of operation of a group 1 of sevencells 2 of a cellular communication system. For convenience, the cellshave been identified by the letters A.B.C.D.E.F, and G. Each cellincludes a beacon 3. For convenience also, the beacons 3 have beenindividually identified by the letters A.B.C.D.E.F, and G with thebeacon A being located centrally of the other beacons B through G. Eachbeacon 3 is capable of operating with a unique plurality ofcommunications channels selected from the total number of channelsinvolved in the cellular system. Each such communication channeloccupies a precisely defined frequency band width within the overallsystem.

As so far described a mobile unit 4 when located, for example, in theoperational zone of beacon A is able to communicate with a requiredtelephone number by a communication link involving the beacon A. As thevehicle moves from cell A, for example, to cell B along a routeindicated by the line 5 the cellular network is such the communicationpath portion formed by the beacon A is transferred to the beacon of cellB.

This is effected without the user of the mobile unit being aware of thebeacon transfer.

It will be understood that the complex electronic equipment within themobile unit will be executing channel seeking operations amongst thebeacons involved and likely to be involved with a view to ensuring thatthe necessary transfer between adjacent beacons takes place as and whenrequired. In practice, such transfers could well involve a number ofinterchanges of communication path between beacons whilst maintainingthe user's telephone communication path. In practice, to achieve theinherent electronic operations taking place, the mobile unit needs to beable to respond to any instantaneous relevant input control and datasignals, and also to be able effectively to produce the appropriateresponse signals to maintain and ensure correct operation. In view ofthese requirements it is, as mentioned above, very important that theoperational parameters of any mobile unit utilizing the cellular systemof FIG. 1 should satisfy the operational standards specified for thesystem.

The apparatus of the invention incorporates at least one input signalaerial arrangement which depending upon the configuration of the system,i.e., base station performance monitoring or mobile unit monitoring,either utilizes the so-called `off air` signal namely the base stationtransmitted RF signal or the forward control channel for a voice channelassignment.

Referring now to FIG. 2 which very schematically illustrates in outlineone of the cells, for example cell B, of FIG. 1 to a greatly enlargedscale. This cell incorporates the base station 3B having atransmit/receive aerial arrangement shown at 6. A mobile telephone unit4 is represented by a symbolic vehicle 7 having an associatedtransmit/receive aerial 8.

Also located at the base station is the Cellular System Monitoringapparatus 9 in accordance with the proposals of the invention. Thisapparatus 9 incorporates an arrangement 10 (this can conveniently beregarded as being similar to an aerial even though a direct cableconnection could be utilized) for receiving radio frequency signalsbeing transmitted by the base station 3B to mobile units 4 which latterare at any one time located within the operational ambit of the cell inquestion.

The apparatus 9 incorporates a second aerial 11 arranged for receivingsignals being transmitted by any mobile unit located within theoperational ambit of the cell 3B.

It will be appreciated that the telephone unit of the mobile unit willof necessity be capable of both transmitting and receiving the carrierradio frequency signals of the communication system together withdigital data streams carrying the telephone messages between users ofthe communication system.

In one form of use of the apparatus of the invention, when ever aparticular mobile unit is being called i.e, paged by the base station soas to establish a telephone link with the mobile unit the base stationin simple terms checks that the mobile unit is located within its regionof operation and then allocates a channel, out of the plurality ofchannels dedicated to the cell involved, in which the telephone link isto be made to the mobile unit that has been called.

The apparatus of the invention makes use of these signals in this firstmode of use to `read` the mobile identity number and also the channelwithin which the subsequent telephone link will be made as illustratedat blocks 12 and 14 in FIG. 3.

Following this, once the mobile unit has responded i.e., the telephonelink has been made, and the mobile unit commences to transmit/receive,the signals being emitted/received by the mobile unit are detected bythe aerial 10 as illustrated at block 16.

The apparatus 9 incorporates signal decoding arrangements able to decodefrom the transmitted signals predetermined characteristics/parametersassociated with the operational specification of the mobile telephoneunit as illustrated at block 18.

Thus the apparatus 9 is able to respond to the signals transmitted by amobile unit when it is the latter initiating the telephonic operation.In other words in this particular mode the requisite monitoring iseffected by using the signal link between the base station and themobile unit without necessarily involving signals direct from the basestation.

It will be appreciated that the construction and operation of signaldecoders as electronic units are both so well known that a detaileddiscussion of the construction and operation of such decoders is notrequired.

Similarly, apparatus for measuring, recording, storing and presentinginformation derivable from electric signals and digital data streams arelikewise individually well known so that a detailed discussion is notthought necessary.

The various decoder signals/data streams are conveniently processed bycomputer arrangements so as to produce a tabulated/graphical outputillustrating the operational state of the mobile unit being monitored asillustrated at block 20 in FIG. 3.

It will be appreciated that the apparatus of the invention enablesidentification of faulty mobile units thereby making it possible for anysuch faulty units to be rapidly identified thereby making it readilypossible for such units to be repaired as illustrated at block 22 inFIG. 3.

In a further mode of use of the apparatus of the invention, convenientlyat low level use periods of the communications system, the base stationcan successively page the mobile units as illustrated at block 24whereupon the apparatus of the invention is utilized to monitor thepaged mobile units so as to effect routine checks of the operationalspecifications of the units and thereby provide regular identificationsof any faulty mobile telephone units within the operational ambit of thebeacon.

In a further utilization of the apparatus of the invention the outputand other operational parameters of the base stations thought convenientcan be monitored to identify faulty operating base stations asillustrated by line 26.

It is not essential for the apparatus of the present invention to belocated at a location of a beacon. In fact, the apparatus of theinvention can be sited at any convenient position, provided of coursethe aerials/antennas thereof are able to pick-up the signals from thebeacon.

As mentioned, the apparatus of the invention can have one or the otherof two operational configurations.

A first of such configurations is the use thereof to monitor theperformance of the base station. For this configuration when used with acellular communication system it has been found convenient to use `offair` input via the aerial 10.

The apparatus is provided with decoders suitable for enablingmeasurement of TX carrier Error; Supervisory Audio Tone Frequency andDeviation, Peak Voice and Power Levels. In practice, the powermeasurements are intended to be used with respect to a recorded levelmeasured on the apparatus of the invention when installed at a basestation site. When used in such configuration the apparatus of theinvention makes it readily possible to monitor and identify faulty basestations.

Furthermore, the apparatus of the invention can be arranged to monitorand record transmitted data streams in addition to the already mentionedRadio Frequency parameters.

The second usage configuration is the monitoring of the mobile units.For this purpose the unit incorporates a plurality of the aerials 10.The apparatus of the invention is able to monitor the Forward ControlChannel for a voice channel assignment, from which it records the MobileIdentity Number, Assigned Voice Channel; Mobile Attenuation Code and theSupervisory Audio Tone Colour Code. After which the apperatus of theinvention scans the aerials 10 for a response on the Assigned VoiceChannel from the mobile. If this mobile has been paged (as abovediscussed) then the mobile will respond with the signalling tone. Theapparatus of the invention measures both the frequency and deviation ofthis tone. On every occasion, whether a mobile unit is paged or calls,the apparatus of the invention will measure the returned supervisoryaudio tone frequency and deviation, carrier frequency error, and peakvoice deviation. An RSSI reading is also recorded along with anindication of which aerial 11 was involved.

The apparatus of the invention can also be used to extract the ESN ofthe monitored mobile by monitoring the reverse control channel by way ofthe aerials 11.

In a particular situation, assuming that the mobile unit user dials atelephone number the mobile unit call signal is detected by the mostconvenient beacon (usually the nearest) and the telephone number beingcalled i.e., another mobile unit number or conventional telephone numberis passed by the beacon onto the appropriate called number via theconventional telephone network. Once the called number has respondedi.e., via the conventional telephone network the beacon involved allotsa convenient voice communication channel to the mobile unit involved.Once the voice channel has been allotted the called number response ispassed via the selected voice channel to the mobile unit involved. Theapparatus of the invention is such as be able to respond to theallotment of the voice channel and since the beacon provides, as hasbeen mentioned control information which inter alia identifies thechannel and also the mobile unit involved the mobile unit is readilyidentified for the purposes of the present invention. In practice, thesecontrol signals are in the form of digital signals which can be decodedby any convenient decoder apparatus. A similar routing procedure ariseswhen the mobile unit is called.

We claim:
 1. A method of monitoring operational performance of a mobiletelephone unit in operation within a communications system involving aplurality of control stations by detecting signals passing between themobile telephone unit and a particular control station during suchoperation, the method including the steps of establishing an identity ofthe mobile telephone unit from said detected signals and utilizingpredetermined operational parameters of the detected signals as a sourceof information for monitoring operational performance of thecommunications system to identify a faulty mobile telephone unitautomatically during normal operation of the mobile telephone unit andcontrol station.
 2. The method as claimed in claim 1, wherein thesignals used are radio signals.
 3. The method as claimed in claim 1,wherein identification of the mobile telephone unit is establishedduring initial stages of the establishment of a communication pathbetween the mobile telephone unit and the particular control station ofthe communications system.
 4. The method as claimed in claim 1, furthercomprising the step of recording values of parameters monitored.
 5. Themethod as claimed in claim 1, further comprising the steps ofsuccessively paging the mobile telephone unit from a control station ofthe communications system, and monitoring the mobile telephone unit toeffect routine checks of operational specifications of the mobiletelephone unit, thereby providing regular identifications upon detectionof a faulty mobile telephone unit.
 6. The method as claimed in claim 1,and including the step of detecting for the mobile telephone unit beingmonitored a mobile identity number of the mobile telephone unit and anumber of the channel to which the mobile telephone unit has beendirected to establish a communication path.
 7. A method of automaticallymonitoring operational performance of a mobile telephone unit while themobile telephone unit is in operation within a communications systemincluding a plurality of base stations, the method comprising the stepsof:detecting a first signal transmitted by the mobile telephone unit toa particular base station; determining an identification number of themobile telephone unit from the first signal; detecting a second signaltransmitted by the mobile telephone unit to the particular base stationduring normal operation of the mobile telephone unit; decoding thesecond signal to determine an actual operational parameter of the secondsignal from the mobile telephone unit; and monitoring the actualoperational parameter of the second signal to identify a faulty mobiletelephone unit during normal operation of the mobile telephone unit. 8.The method of claim 7, wherein the second signal is a radio frequencysignal.
 9. The method of claim 7, wherein the step of determining theidentification number of the mobile telephone unit occurs automaticallyduring an initial stage of the establishment of a communication pathbetween the mobile telephone unit and the particular base station of thecommunications system.
 10. The method of claim 9, wherein the seconddetecting step and the decoding step take place during normal operationof the mobile telephone unit.
 11. The method of claim 7, furthercomprising the step of recording values of the actual operationalparameter of the second signal decoded during the decoding step.
 12. Themethod of claim 7, further comprising the steps of successively pagingthe mobile telephone unit from a base station of the communicationssystem to effect routine checks of the operational parameter of themobile telephone unit, and identifying a faulty mobile telephone unit.13. A method of automatically monitoring operational performance of amobile telephone unit while the mobile telephone unit is in operationwithin a communications system including a plurality of base stations,the method comprising the steps of:detecting a signal from the basestation, determining an identification number of the mobile unit fromthe signal detected from the base station, determining an allocatedchannel for the mobile telephone unit from the base station signal,detecting a signal transmitted by the mobile telephone unit to the basestation on the allocated channel during normal operation of the mobiletelephone unit, decoding the signal from the mobile telephone unit todetermine an actual operational parameter of the signal from the mobiletelephone unit, and monitoring the actual operational parameter of thesignal to identify a faulty mobile telephone unit during normaloperation of the mobile telephone unit.